Lawn mower sharpener



Aug. 24, 1943. A. slLFEN 2,327,827

LAWN MOWER SHARPENER Filed Mami 1o, 1941 Patented Aug. 24, 1943i i UNITED STATES b?A'I`l`.l\1'l` OFFICE Lawns/rowers SHAItrENER Alfredfsilfen, Berkeley, Ill."` applicaties Maren 1o, 194.1, serialNo. 382,508

` 1 claim. v(o1. '7e-aai) The present invention relates generally to Sharpeners for conventional or' standard lawn mowers. More particularly the invention relates to that type of lawn mower 'Sharpener which comprises a metallic bar witha U-shaped guideV at one end thereof and a longitudinally adjustable file retaining bracket at its other end,` and is used by first manipulating the bar in such manner as to bring it into a transverse position with respect to the'bla'de equipped rotor of the lawn mower to be sharpened and at the same time' to bring the U-shaped guide into straddled relation with'th'e tie rod between the Vgearhousings r off the IZIOWer and the file into engagin'glor contacting relation with one of the' 'spiral blades of the rotor; and then grasping the ends of the VbarV and shifting the lbar back and forth between 'the wheels of the lawn mower in order to cause the file to move along the one blade and sharpen the latter.

One object or the invention is to provide a lawn mower 'Sharpener of this type which 'is Vvan improvement upon; and has certain vinherent advantages over, previously designed sharpeners of the same general character. Y

Another object of the .invention 'is to provide a lawn mower Sharpener of the type under consid# eration in the U-shaped lguide is .formed as an integral part of the `har by striking upwards or otherwise shaping one end of the bar and carries between the upper ends of the side 'pieces thereof a cross pin which servesr `to prevent spreading Aof the side 1pieces Vof the guide and supports 'a freely rotatable roller which 'is adapted to ride on the tie rod of the .lawn `mower to be sharpened. and facilitates sliding movement-or shift oi the bar back and forth between the wheels of the mower. A further object `of the inventionis -to provide a lawn mower Sharpener of .the last mentioned type .and character which the bracket carrying end of the .bar `extends rdowmf/artis at an angle of approximately 170 with 'respect to the fend with the U-shaped `guide in order properly or most advantageously to position the 'ille withrespept to the spiral blade that lis :to Abe sharpened. :A :still further 'object of the invention is to 1910# vide a lawn mower :Sharpener which not ionly is essentially simple indesign Aand f'may 'be .manu-- factured at a low land reasonable cost but also rugged and durable andeffe'ct'ively and efficiently fulfills its intended purpose. l Other objects -o'f the inventionand the various advantages and characteristics of the present law-n mower -sharpener will --be apparent from a consideration ofthe following detailed description. f

The invention consists inthe `several novel features which are hereinafter set forth and are more particularly defined by the claim at the conclusion hereof. i

lin the drawing` which accompanies and forms a part of this specification or disclosure and in which like letters and numerals of reference denote corresponding parts throughout `the several views:

Figure 1 is aplan view `of a lawn mower having applied thereto a Sharpener lembodying the invention;

Figure 2 is a vertical transverse section taken on Vthe line 2-2 of Figure 1 and showing .the Sharpener in its operative or blade sharpening position;

Figure 3 isa perspective ofthe Sharpener, illustrating in detail the construction and design of the par, the U-shaped roller equipped guide and the ille retaining bracket;

Figure 4 is a perspective view of the bracket.; and

Figure '5 is ya vtransverse sectionjof the brac'ket. The Sharpener 4which iss'hown in the drawing constitutes the preferred form or embodiment of the invention. llt is illustrated in connection with a lawn mowerL and serves, as described more in detail hereinafter,` 'as a medium for sharpein'n-gk the rotatable 'bladesof the lawn mower. As shown or illustrated in the drawing thev lawn mower Lis 'of conventional or standard design and comprises a horizontally extending rotor l, a pair of .ground wheels l1, at vthe ends of the roter, ,and a handle i2. Gearing (not shown) in housings 13 Vservesto drive the rotor from `the wheelsduring forward travel 4of the lawn mower. in addition to the Aaforementioned parts the 4lawn mower comprises a tie rod 14 between Vthe gear housings l'3 and a fixed .horizontally` extending knife bar l5. Thfe rotor is provided with a'plurality of equidistantly spaced .spira-l blades I6 and these, 'as well understood in the =art, are adaptedfin connection with forward travel of the lawn mower successively tof traverse the knife bar l5 and effect the `desired cutting of the grass. The knife bar islocated at th'e bottom of .thejlawn mower and the tie rod I4 is located above and slightly forwardly of the blade equipped rotor.

As its partsthe Sharpener comprises abar, a U-shaped guide 1 at one 'of thejbar," and a longitudinally adjustable *bracket 8 nn the .other end ofthe "bars The bracket serves .asa retainer for a'le 9;

The bar 6 is formed of fiat metal stock and is adapted in connection with use of the sharpener to be placed in a transverse position over the lawn mower rotor, as shown in Figures 1 and 2. It consists of a short straight end part lil and a long straight end part II and has the guide 'I formed as an integral part of it. The guide is formed by striking upwards or otherwise shaping the portion of the bar directly inwards of the short end part I and serves as a medium for connecting together the two end parts I and II. It is adapted in connection with use of the Sharpener to straddle and slide lengthwise of the tie rod I 1 of the lawn mower L and consists of a pair of laterally spaced parallel side pieces I2 and I3 and an upper cross piece I4 (commonly called a shrub bar). The side piece I2 is approximatelytwice as long as the side piece I3 and extends between and joins the inner end of the end part IIJ and the outer end of the cross piece Ill. It extends at true right angles to the end part II] and is truly normal to the upper cross piece Ill. The side piece I3 of the guide 'I extends between and is joined to the inner end of the long end part II of the b ar 6 and the inner end of the upper cross piece I4. It extends 'at true right angles to the cross piece and is held in spaced relation with the side piece I2 by the upper cross piece It. The cross piece isrof such lengththat the two side pieces are spaced a sufficient distance apart to accommodate between them lawn mower tie rods of various sizes, shapes and thicknesses. In orderto facilitate sliding `movement of the guide with respect to the tie rod I4 in connectionwith use of the Sharpener a roller I5 is provided.V This -roller directly vunderlies and extends in parallel relation with the upper cross piece Ill of the guide -'I and is rotatably supported on a pin l5. The lattery extends between the two sidel pieces of the guide and in effect formsa tie rod for rigidly cross con` necting the two side pieces and preventing spreading of the latter during use of the Sharpener. The ends of the pin project through coaxial or aligned holes in theupper ends of the side pieces I 2 and I3 'and are up-'set or riveted-over in order to prevent axial displacement of the pin with respect to the guide.` When the Sharpener is in use the roller I5 rides upon the upper portion of the lawn mower tie rod 14,5 the side pieces I2 and I3 extend vertically, and the short endr part IU of the bar 6 extends horizontally, as shown in Figure 2. Because the roller is rotatably supported by way of the pin the guide is permitted tol travel freelyI along the tie rod. The guide serves to restrict or limit endwise or lengthwise movement'of the bar during use of the sharpener. Because the side piece I2 of the U-shaped guide 'I is approximately twice as long as the side piece I3 it effectively hooks around the front portion of the lawn mower tie rod'. I 4 when the Sharpener is in use and hence prevents the guide 'I from jumping off or leaving the tie rod in connection with .a blade sharpening operation. The end part II of the bar is approximately three times longer than the end part I0 and carries the le retaining bracket 8. It is bent slightly downwards so that it extends at substantially a y170 angle with respect to the end part I0. Because the side 'piecev I3 of the guide I is shorter than the side piece I 2 and the end part I I of the bar extends downwards at a slight angle the Sharpener as a whole may be readily applied to any standard or conventional lawn mower and the file'which,as shown in Figure Shiitsatlyz against the bottom face of the end part II, is properly positioned with respect to the edge of the blade to be sharpened during use of the sharpvener. As a general rule the edges of lawn mower blades are slightly bevelled, as shown in Figure 2. By having the end part II of the bar angularly positioned with respect to the end part I Il the le 9 `in connection with use of the Sharpener, is so held or positioned that it fits properly and flatly against the edge of the blade to be sharpened and thus sharpens the blade with the proper or desired bevel. The outer extremities of the end parts I0 and II of the bar'are bent and curved upwards to form handles Il whereby the bar may be gripped between the thumbs and forengers when it is shifted back and forth for blade sharpening purposes. Becausey of the design of the U-shaped guide 'I and the angularity and and length of the long end part II of the bar 6 the two handles I1 are horizontally aligned during use of the Sharpener and the user of the sharpener is thus better able to shift the bar 6 back and forth.

The bracket 8 surrounds and is slidable length-' wise of the long straight end part II of the bar 6. It serves in addition to holding or retaining the nie s, to guide the blade to be sharpened with respect to the file and comprises` a diamond shaped top piece I8, a pair of opposedoppositely or reversely positioned Wedge shaped bottom pieces I9 and a pair of U-shaped tab-like connecting lpieces 20 between the top piece and the bottom pieces. The top piece I8 overlies the top face of the end part I I of the bar and has a central internally threaded hole through which a wing equipped clamp screw 2I extends. The bottom pieces I9 are spaced laterally apart so as to define or form between them a diagonal/guide channel 22. Thischannel is angled in conformity with the spiral of the blades I 6 of the lawn mower rotor and is adapted in connection with use of the Sharpener to receive the blade to be sharpened and cause the blade in connection rotate rst back and then forwards. The ille 9 overlies the bottom pieces I9,as shown in Figure 3, and fits flatly against the bottom face of the end part II, as hereinbefore pointed out. When the screw 2I is tightened the upper piece I8 of the bracket is urged away from the end part I I and thiscauses the bottom pieces to hold the `le in clamped relation with said end part.

The file is preferably held by the bracket so that y the central portion thereof traverses or extendsv across the top of the guide channel 22. ,Adjustment of the bracket and file is eifected by loosening the wing equipped screw 2I and then sliding the bracket and file in one direction or the other so as properly to position the le with respect to the U-shaped guide 1. The corners of the wedge shaped bottom pieces are rounded.V

or curved so that the guide channel 22 has flared ends. sharpened travels freely alongthe guide channel during a sharpening operation. The connecting pieces 20. extend between and serve toY connect the outer corners of the wedge shaped-bottoni pieces I9 and two of the corners of the top piece I8. They are positioned one diagonally opposite the other and permit rotative adjustment of "the bracket as well as lengthwise adjustment of the bracket with respect bar. l In using the Sharpener the bar 6 is manipu- By having flared ends the' blade to bev to the end part IIf of; the

lated so as to bring the U-shaped guide I into straddled relation with the tie rod I4. After proper positioning of the guide the bracket is properly adjusted and then manipulated so as to bring the blade to be sharpened between the bottom pieces I9, i. e., into the guide channel 22. When the Sharpener is properly positioned the handles I'I at the outer extremities of the bar 6 are gripped and the bar is shifted back and forth between the Wheels of the lawn mower L. During such movement of the bar the roller I5 rides along the tie rod I1 and the file 9 engages and serves to sharpen the edge of the blade within the guide channel 22. After sharpening one blade of the rotor the Sharpener is used to sharpen the other blades. By adjusting the bracket and le the Sharpener may be used to sharpen various types, styles or sizes of lawn mowers.

The herein described lawn mower Sharpener consists of but a minimum number of parts and hence may be manufactured at a low and reasonable cost. It eiectively and eiiiciently fulfills its intended purpose and is characterized by the fact that it is rugged and durable. It is further characterized by the fact that it is safe to use because the U-shaped guide 1, due to its design and shape, is not likely to jump off the tie rod I4 of the lawn mower in the event that the file 9 encounters a burr on the mower blade being sharpened.

The invention is not to be understoodtas restricted to the details set forth since these may be modified within thescope of the appended claim without departing from the spirit and scope of the invention.

Having thus described the invention what I claim as new and desire to secure by Letters Patent is:

A Sharpener of the back and forth movement type designed for use in sharpening a lawn mower having a horizontal rotor with spaced apart bevel edged peripheral blades and in addition a horizontal tie rod above and slightly forwards of the rotor, and comprising a one-piece flat metal bar having the portion thereof directly inwards of one of its end parts bent upwards to form an integral inverted U-shaped tie rod straddling guide with the outer side piece thereof materially longer than, and in parallel relation with, the inner side piece, said bar having its endextremities bent upwards to form handles, and in addition having said one end part extending at right angles to the outer end piece of the guide and its other end part of materially greater length than said one end part and extending downwards at an angle of approximately 170 with respect to said one end part, a cross pin underlying and extending lengthwise of the crosspiece of the guide and having the ends thereof xedly secured to the upper ends of the guide side pieces so that it serves to prevent spreading of said side pieces and also the end parts, and means on, and adjustable longitudinally of, said other end part vof the bar for retaining a blade sharpening le against the bottom face of said other` end part and also guiding the blade at the top of the lawn mower rotor with respect to the file during use of the Sharpener, said bar being adapted when in its normal operating position with the guide in straddled relation with the tie rod to have said one end part project forwards from the tie rod and extend horizontally and its said other end part extend rearwards and downwards over said blade at the top of the rotor, said other end part of the bar being of such length that when the bar is in its normal operating position the handle at its outer extremity is in substantially the same horizontal plane as the handle at the outer extremity of said one end part.

ALFRED SILFEN. 

